The broad long-term objectives of this research are 1.) to describe alterations of the normal lens plasma membrane-associated cytoskeleton which occur as a consequence of selenite-induced cataract, and 2.) to describe alterations which occur in the distribution and activity of lens calpains. The specific objectives of this proposal will be to isolate fram rat lenses, distinct membrane fractions, which may represent different domains of the lens plasma membrane from normal and cataract bearing animals. Each of these fractions contains its own characteristic set of cytoskeletal proteins, which reflect the normal architecture of the membrane-associated cytoskeleton associated with that particular membrane fraction or domain. Interference with this architecture is associated with cataract. It is currently unknown how these cytoskeletal elements interact with the lens plasma membrane, or special domains of the lens plasma membrane. Four distinct plasma membrane fractions will be isolated from the rat lenses, and using electrophoresis and immunochemical methods, specific cytoskeletal peptides will be identified and quantitated in each different membrane fraction from normal and cataractous lenses. Immunochemical methods will also be used to determine the membrane distribution of lens calpains, and a method which allows measurement of enzyme activity in polyacrylamide gels will be used to determine the level of activity of these calpains. This research will provide basic information on the composition of the lens plasma membrane-associated cytoskeleton. Also, these studies will describe changes in the cytoskeletal network which are associated with the formation of cataracts. It is anticipated this information will be useful in the understanding of human senile cataract.